Identification and analysis of low light tolerant rice genotypes in field conditions and their SSR-based diversity in va
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Ó Indian Academy of Sciences (0123456789().,-volV) (0123456789().,-volV)
RESEARCH ARTICLE
Identification and analysis of low light tolerant rice genotypes in field conditions and their SSR-based diversity in various abiotic stress tolerant lines SEBANTEE GANGULY, SHOUMIK SAHA, SATHISH VANGARU, SHAMPA PURKAYASTHA, DIBAKAR DAS, ARUP K. SAHA, ANIRBAN ROY, SUBHADEEP DAS, PRABIR K. BHATTACHARYYA, SUBHRA MUKHERJEE and SOMNATH BHATTACHARYYA* Genetics and Plant Breeding, Crop Research Unit, Bidhan Chandra Krishi Viswavidyalaya, Mohanpur 741 252, India *For correspondence. E-mail: [email protected]. Received 11 June 2020; revised 13 August 2020; accepted 4 September 2020 Abstract. The yield potentiality of kharif rice is not completely used even under well-irrigated agro-ecosystem, mainly due to low irradiance by overcast cloud throughout the growing season in eastern India. We observed more than 50% yield reduction compared to the performance of 100 high-yield genotypes for consecutive three years both under open and 30–35% reduced light intensity, mainly by 34%, 25% and 12% reduction of panicle number, grains per panicle and test weight. As per the analysis of variance, genotypic variance explained 39% of the total yield-variation under shade with 58% heritability. Overall, the maintenance of equal panicle per plant in both open and shade has the highest association with shade tolerance. Purnendu, Sashi and Pantdhan19 showed less than 28% yield-reduction by maintenance or even by increasing grain numbers under shade and test weight. On the other hand, maintenance of an equal number of panicle under both situations was the key to the tolerance of Bhasamanik, Sasarang, Rudra and Swarnaprabha. As compared to open, we noticed the improvement of chlorophyll a and b under shade but saw a poor correlation with the shade tolerance index. Comparing the net photosynthesis rate (Pn) in eight genotypes, we found the best tolerant line ranked last with least Pn at low light intensity (\400 lmol m-2 s-1). We also identified diverse parental combinations between newly identified shade tolerant and abiotic stress tolerant high-yielding rice lines following diversity analysis using 54 simple-sequence repeats. Thus, the selected tolerant lines from a large set of genotypes with different adjustment ability to keep up high yield under low light intensity can be used for physiological, molecular analysis as well as pyramiding of traits. Keywords.
shade-tolerance; panicle number; rice; diversity.
Introduction In India and South Asia, rice is cultivated mainly in rainy season (kharif rice) when it receives significantly less irradiation (below 500 lm/m-1/s-1) due to the overcast cloud throughout the growing season. Irradiance reduces further according to location and solar movement within a day. Low irradiance reduces the photosynthesis vis-a-vis dry weight, as rice exhibits optimum net photosynthesis at the range of 800–1000 lm/m-1/s-1 (Murchie et al. 2002; Kasajima et al. 2011). Depending on the stage of rice, low light intensity can redu
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